There is an increasing popularity in liquid packaging systems that utilize a penetrable container and a spiked outlet connector. The container may be of a semi-rigid cardboard or a flexible plastic sheet. The spiked outlet is typically a tap that penetrates and seals against the cardboard or plastic sheet wall of the container. These systems have a wide variety of uses, ranging from the aseptic packaging of ordinary food such as fruit juice, packaging enteral food and packaging pharmaceutical preparations such as fluids for intravenous or peritoneal delivery.
Among the advantages of these systems are their light weight, low cost and simple operation. Further, in the case of the plastic sheet containers, the containers can be transported in an empty and collapsed condition in a very small space and then filled prior to use. After use, the container can again be collapsed and then disposed of in a small space. The plastic sheet containers also lend themselves to sterile packaging using automated fabricating and filling machines that are known in the art.
A principal disadvantage to such systems is the occasional difficulty and expense of obtaining access to the liquid that is packaged in them. Access is typically obtained through a spiked connector that is especially designed for that purpose. The spiked connector may cost more than the container itself. It is usually not reusable, due to concerns of sterility or sanitation. Further, the spiked connector may not always seal perfectly against the wall of the container, thereby allowing the connection to leak. While the seal can be improved using rubber based materials in the container wall, such materials may have insufficient strength or resistance to light degradation or may be difficult to sterilize or to manufacture using heat sealing techniques.
An example of a spiked connector used in tapping semi-rigid aseptic cardboard packages is disclosed in U.S. Pat. No. 4,826,500 by Rautsola for Enternal Nutrient Delivery System. The Rautsola device includes a spike to penetrate the container wall, a liquid passageway through the spike, a make-up air passageway through the spike and a set of threads on the outer circumference of the spike to engage and seal against the container wall. An improvement over this concept is disclosed in U.S. Pat. No. 5,000,349 by Rautsola for Aseptic Package Tap. In the later Rautsola patent, the spike threads as a means for engaging and sealing against the container wall are replaced with a cam arrangement that cooperates with a sleeve that is axially compressible and radially expandable to engage and seal against the punctured hole of the wall. The later Rautsola patent avoids the need to thread the spike into the container. The Rautsola devices are designed primarily for use with semi-rigid cardboard containers, and not for use with flexible plastic sheet containers.
An example of a system for use with flexible plastic sheet container is in U.S. Pat. No. 4,567,999 by Hjertman et al. The Hjertman patent discloses an adhesive fitting that can be attached to the exterior surface of the plastic sheet. A point slidably mounted in the fitting and surrounded by a tubular sleeve pierces the plastic sheet, and then the point is withdrawn while the sleeve remains in the plastic sheet so that liquid can flow through the sleeve. Unless the Hjertman device is adhered perfectly to the sheet, it will leak liquid. Also, the device appears somewhat complicated and expensive to manufacture.
Other devices exist for tapping a flexible plastic sheet container, including U.S. Pat. Nos. 4,640,425 by Cabernoch, U.S. Pat. No. 4,553,971 by Ashley, and 4,830,205 by Hammond. The Cabernoch and Hammond patents are for containers with a sealable gusset to form a pocket to store an attached nursing nipple. The Ashley patent is for a container having a sealable pocket to contain an attached frangible seal that can be pierced by a needle. Each of these devices require a perfect seal between the fitting and the plastic sheet to prevent any leaking.